Interface for laser eye surgery

ABSTRACT

A laser surgery system having a computer control system coupled to a laser subsystem and a patient seat. The control system is coupled to the laser through a laser alignment system. The control system can be coupled to the patient seat through a patient alignment system. The control system sends a nominal position signal to move the patient seat, laser subsystem, or both so that the patient&#39;s first eye is moved into substantial alignment with the laser beam axis. The control system can send a second nominal signal to move the patient&#39;s second eye into substantial alignment with the laser beam axis. The control system can optionally comprise both an operator display and an assistant display. The assistant display provides real-time information to an assistant positioned at an assistant station adjacent the patient seat. The control system can be programmed to display edit fields with different colors to provide an obvious indication of the refractive information of the eye. The control system can comprise an operator input for providing a pre-determined secondary ablative treatment. If it is determined that the first ablative treatment did not completely remove the epithelial layer from a target region, the operator actuates the operator input to deliver the secondary ablative treatment.

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] The present application is a divisional of and claims the benefitfrom U.S. patent application Ser. No. 09/534,849, filed Mar. 28, 2000which claims benefit of U.S. Provisional Patent Application No.60/128,122, filed Apr. 7, 1999, under 37 C.F.R. §1.78, the completedisclosure of which are incorporated herein by reference for allpurposes.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSOREDRESEARCH OR DEVELOPMENT

[0002] Not Applicable

REFERENCE TO A “SEQUENCE LISTING,” A TABLE, OR A COMPUTER PROGRAMLISTING APPENDIX SUBMITTED ON A COMPACT DISK.

[0003] Not Applicable

BACKGROUND OF THE INVENTION

[0004] The present invention relates generally to methods, systems anddevices for performing corrective eye surgery. More particularly, thepresent invention relates to improved computer and laser systeminterface methods, computer interface programs, and operator systeminterfaces. The present invention is particularly useful for enhancingthe speed, ease, safety, and efficacy of laser eye surgical proceduressuch as photorefractive keratectomy (PRK), laser in situ keratomileusis(LASIK), and the like.

[0005] Laser eye procedures typically employ ultraviolet or infraredlasers to remove a microscopic layer of stromal tissue from the corneato alter its refractive power. Excimer lasers (i.e. ultraviolet laser),such as the VISX STAR™ or STAR S2™ laser system, use argon and fluorinegas to create a non-thermal laser light to break molecular bonds, in aprocess known as photoablation. Ultraviolet laser ablation results inthe photodecomposition of the corneal tissue, but generally does notcause significant thermal damage to adjacent and underlying tissues ofthe eye. The photoablation removes stromal tissue to change the contourof the cornea to correct myopia (near-sightedness), hyperopia(far-sightedness), and astigmatism.

[0006] In general, existing laser eye surgery systems have included anoperator interface for use by the laser system operator in setting-up,controlling, monitoring, and generally directing the laser treatment ofthe patient's eyes. The safety and efficacy of a photorefractiveprocedure depends in part on the operator's ability to interact with thelaser control system using the operator interface. The costs of eachsurgical procedure are significantly affected by any unnecessary timedelays in setting-up or directing the procedure. Unfortunately, existingoperator interfaces are less than ideal in a number of aspects.

[0007] The photoablation of corneal tissues benefits from precisealignment between the eye and a therapeutic laser. Known laser eyesurgical alignment systems typically have a patient seat or bed with thepatient seated, lying down, or reclined in a supine position. To alignthe patient with the laser beam, the operator must manually adjust theseat or bed into alignment with the laser. Additionally, because theseat or bed often has limited speeds and/or ranges of motion thealignment procedure can be quite time consuming—especially when botheyes are to be treated.

[0008] Known operator interface display systems also suffer from avariety of additional disadvantages. For example, it may not always beas clear as would be desirable what type of refractive error and /orcorrection is represented on a controller display. Specifically,hyperopia and myopia designate alternative refractive errors which areopposite in nature, but it may not always be clear whether a negativevalue in a hyperopic display field designates a myopic characteristic orcorrection or a hyperopic characteristic or correction. An errorintroduced at this point would result in the patient's refractive errorbeing doubled instead of corrected.

[0009] Laser ablation of the epithelial layer, an outer layer of theeye, is often performed before the re-sculpting ablation begins. Whilethese epithelial ablations are now controlled from the operatorinterface, it can be time consuming to reconfigure the system if theepithelial layer is not completely removed from with the initial laserablation treatment. Finally, known laser refractive surgery systems donot always provide sufficient information to everyone involved in theprocedure. In addition to the system operator, the patient and assistantmight benefit from procedure and/or system information which iscurrently directed only to the operator. These limitations detract fromthe speed, safety, and comfort of known refractive surgical techniques.

[0010] For these reasons, it is desired to provide an improved interfacefor laser eye surgery. In particular, it is desired to have a systemcapable of automatically aligning the patient's eye with the laser.Furthermore, it would be desirable to have a system which quickly andautomatically aligns the patient's second eye after the first eye hasbeen treated. It is also desired to have a system interface which wouldallow the operator to easily determine the refractive characteristicsthat have been entered. It would further be desirable to provide asystem in which the assistant can view system information regarding theprocedure, while still being near the patient. It would further bedesirable if such a system could easily control the complete ablation ofthe target portion of the epithelial layer. At least some of theseobjectives will be met by the system and method of the present inventiondescribed hereinafter and in the claims.

BRIEF SUMMARY OF THE INVENTION

[0011] The present invention generally provides improved laser eyesurgery devices, systems, and methods. The invention generally enhanceslaser eye treatment by using methods and interfaces which increasetreatment efficiency and provide improved system features.

[0012] In one aspect, the present invention provides a laser refractivesurgery system having a laser that produces a laser beam. The laserdefines a longitudinal axis along the path of the laser beam. A patientseat is movable along at least the X and Y horizontal directions. Acontrol system is coupled to the patient seat and laser andautomatically positions the seat at a nominal position. At the nominalposition, the seat substantially aligns a patient's first eye with thelaser axis. In a particular embodiment, the control system can beadapted to automatically substantially align a second eye with the laseraxis.

[0013] In another aspect, the present invention provides a laserrefractive system having a laser which produces a laser beam thatdefines a longitudinal axis. A patient seat or bed is contoured tosupport a patient in a patient position so that first and second eyes ofthe patient are near first and second nominal axes, respectively. A seatalignment system couples the seat to the laser. The patient alignmentsystem moves the seat, the laser, or both, in response to a nominalposition signal so that the beam axis is aligned with the first opticalaxis.

[0014] In yet another aspect, the present invention provides a methodfor positioning a patient for refractive eye surgery. The methodincludes the steps of automatically positioning a patient in a firstnominal position. In the first nominal position, the patient's first eyeis substantially aligned with a laser. The patient is then automaticallypositioned to a second nominal position. In the second nominal position,the patient's second eye is substantially aligned with the laser. Inmost embodiments, the patient is automatically moved to the secondnominal position after the first eye has been treated.

[0015] In another aspect, the present invention provides a method foraligning a patient for laser surgery. The method comprises placing aseat in a patient loading position. A control system is activated tomove the seat to a first nominal position in which the patient's eye issubstantially aligned with a laser beam axis.

[0016] In a further aspect, the present invention provides a laser eyesurgery system. The system includes a laser for producing a laser beam.A patient seat or bed is positioned adjacent the laser. A control systemis coupled to the laser. The control system has laser operation controlsand displays information about the treatment. An assistant display iscoupled to the control system, wherein the monitor is viewable fromadjacent the patient seat or bed so an assistant can monitor thetreatment from the assistant station.

[0017] In another aspect, the present invention provides a method ofproviding treatment information of a laser eye procedure to an operatorand an assistant adjacent a patient. The method comprises monitoringtreatment information of a laser eye procedure. The treatmentinformation is displayed in real-time on a computer control system andan assistant display. The assistant display screen is alignedsubstantially orthogonal to the computer control system so the assistantadjacent the patient can view the information displayed on the assistantdisplay.

[0018] In yet another aspect, the present invention provides a methodfor performing corrective eye treatment. The method includes the step ofdirecting a laser beam at a corneal region of an eye of a patient.Information about the treatment is displayed to the operator inreal-time on a control station display. Information about the treatmentis also displayed to an assistant in real-time on an assistant display,such that the assistant can view the information while adjacent thepatient.

[0019] In a further aspect, the present invention provides a laser eyesurgery system having a laser system for producing a laser beam forrefractive surgery on a cornea. A computer control station, having anoperator interface and control system, is coupled to the laser system tomonitor and control the laser system. Typically, the computer controlsystem is adapted to display on the operator interface a first colorwith fields displaying myopic refractive information and a second colorwith fields having hyperopic refractive information. The first color andsecond color are preferably different colors.

[0020] In another aspect, the present invention provides a method ofdisplaying refractive information. The method includes the stepdisplaying refractive information on an edit field. A first backgroundcolor is provided for the edit fields displaying myopic refractiveinformation. A second background color is provided for the edit fieldsdisplaying hyperopic refractive information.

[0021] In yet another aspect, the present invention provides a systemfor removing an epithelial layer from a target region in a cornea duringphotorefractive surgery. The system includes a laser which produces atissue-ablative beam. The laser provides an initial uniform epithelialablative treatment over the region and a refraction alteringre-sculpting ablative treatment. A control system that is adapted tomonitor and control the ablative treatments is coupled to the laser. Anoperator input is coupled to the control system, such that uponactuation of the operator input, the control system actuates the laserto provide an incremental epithelial ablative treatment.

[0022] In a further aspect, the present invention provides a system forremoving an epithelial layer from a target region in a cornea. Thesystem includes a laser which provides a first ablative treatment and asecondary ablative treatment. A control system is coupled to the laserand is adapted to monitor and control the tissue ablative treatments. Anoperator input for providing a secondary ablative treatment is coupledto the control system. Upon actuation of the operator input, the laserprovides a secondary ablative treatment. In a preferred embodiment, theoperator input comprises a button mounted to the control system.Actuation of the button can deliver a pre-determined amount of thetissue ablative beam.

[0023] In yet another aspect, the present invention provides a methodfor removing an epithelial layer from over a stromal layer in a cornea.The method includes irradiating a target region of the epithelial layerwith a first amount of ablative radiation. If it is determined that thefirst amount of ablative radiation did not completely remove theepithelial layer from the target region, the target region of theepithelial layer is irradiated with a predetermined secondary amount ofablative radiation. In a preferred embodiment, a button is depressed todeliver the secondary amount of ablative radiation.

[0024] These and other aspects of the invention will be further evidentfrom the attached drawings and description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]FIG. 1 illustrates a simplified cross-sectional view of a humaneye;

[0026]FIG. 2 illustrates a cross-sectional view of the five layers ofthe cornea;

[0027]FIG. 3 illustrates a perspective view of a laser eye surgerysystem in accordance with the principles of the present invention;

[0028]FIG. 4 illustrates a plan view of the system of FIG. 1 showing therelative orientation assistant display and the operator display;

[0029]FIG. 4A illustrates an embodiment of the assistant display;

[0030]FIG. 4B illustrates another embodiment of the assistant display;

[0031]FIG. 5A illustrates an interface display having a first backgroundcolor for a screen displaying myopic refractive information;

[0032]FIG. 5B illustrates an interface display having a secondbackground color for a screen displaying hyperopic refractiveinformation;

[0033]FIG. 6 illustrates a control station having a physical button anda button actuatable by a cursor;

[0034]FIG. 7 shows a touch screen having a sample treatment screen witha “deeper button” to incrementally ablate corneal tissue to completeremoval of the epithelium in preparation for a re-sculpting procedure;

[0035]FIG. 7A illustrates a joystick setup which can control the grossadjustment mechanism and/or the fine adjustment mechanism;

[0036]FIG. 8A illustrates an embodiment of the contoured patient seatadjustable along the Z-axis;

[0037]FIG. 8B illustrates an embodiment of the contoured head pillow;

[0038]FIG. 8C illustrates a headrest control;

[0039]FIG. 8D illustrates a contoured patient seat in a loadingposition;

[0040]FIG. 8E illustrates a patient seat in a nominal position,substantially aligned with the laser axis, wherein a patient's first eyeis within the range of motion of the laser;

[0041]FIG. 8F illustrates a laser axis aligned with a patient's firstoptical axis;

[0042]FIG. 8G illustrates the laser axis in a second nominal position,aligned with a patient's second optical axis;

[0043]FIG. 9 schematically illustrates an embodiment of the invention;

[0044]FIG. 10 is a flow chart of the process of aligning a patient withthe laser axis;

[0045]FIG. 11 is a flow chart of the process of ablating the epitheliallayer using the deeper button;

[0046]FIG. 11A illustrates a complete epithelial layer in the targetregion being treated by ablative treatment;

[0047]FIG. 11B illustrates an epithelial layer that was not completelyremoved by the first ablative treatment, which is being treated by asecondary-ablative treatment; and

[0048]FIG. 12 shows a touch screen having a second sample treatmentscreen after the epithelial layer of the target region has been removed.

DETAILED DESCRIPTION OF THE INVENTION

[0049] The present invention provides systems, methods and interfacesfor improving the laser treatment of the eye. More specifically, thesystems and interfaces of the present invention are particularly suitedfor use on the STAR™ and STAR S2™ Excimer Laser System which arecommercially available from VISX, Incorporated of Santa Clara, Calif.Additionally, the systems and interfaces of the present invention aresuitable for use with laser systems manufactured by Chiron Vision ofIrvine Calif., Summit Technology of Watertown, Mass., Nidek Co., Ltd. ofGamagori, Japan, Meditec of Heroldsberg, Germany, LaserSight of Orlando,Fla., Autonomous Technologies Corporation of Orlando, Fla., and thelike. The systems may be programmed to perform the methods of thepresent invention by providing a computer program in the form of atangible medium comprising computer readable code setting further themethods described in more detail below.

[0050]FIG. 1 illustrates a simplified view of an eye. The cornea 69covers the pupil and provides the focusing power to the eye. The pupil63 is located behind the cornea and controls the amount of lightentering the eye. The lens 67 is a clear structure located behind thecornea and provides fine-tuning for focusing. The retina 64 transmitsthe images to the brain. Myopia occurs when the eye is too long for thecornea's curvature. Light rays entering the eye do not come to a sharpfocus on the retina, but instead focus further forward of the retina. Incontrast, hyperopia occurs when the eye is too short for the cornea'scurvature and light rays entering the eye focus behind the retina.

[0051] Specifically, as shown in FIG. 2, the cornea is composed of fivelayers of tissue. The cornea is comprised of the epithelial layer 70,the lamina limitans anterior (also known as Bowman's layer 72), thestromal layer 74, lamina limitans posterior (also known as Descemet'slayer 76), and the endothelium 78. The outermost layer, the epitheliallayer 70 is approximately 50 μm thick. For patients undergoing aphotorefractive keratectomy (PRK), the epithelial layer of a targetregion is removed or displaced from over the pupil before the stromallayer 74 is shaped to correct the contour of the cornea.

[0052]FIG. 3 illustrates a laser surgery system embodiment in accordancewith the principles of the invention. Laser eye surgery system 100 isdesigned for performing corrective laser surgery with an excimer laserto reshape the surface of the cornea to correct refractive visionerrors. In general, the surgery system of the present invention includesan operator control station 21 having a computer control system 22 andlaser operation controls 23. The computer control system 22 generallycomprises a conventional PC computer coupled to a keyboard 32, anoperator display 30, an assistant display 34, and standard computerinput and subsystem components (e.g., flexible and hard disk drives,CD-ROM, an internet connection, modem, memory boards and the like).Various input devices, such as a touch screen, joystick, mouse, footpedals, and the like, can be used to input information or send controlsignals to the control system. Such input devices will often be used todownload and execute a computer code from a tangible storage media, suchas a computer program in the form of a computer-readable floppy disk, aCD-ROM, a cartridge, a data tape, or other conventional medium, toembody the methods of the present invention. Additionally, the computer22 can be programmed using any conventional programming technique toencode the methods for the present inventions, as described in moredetail below. Further details of suitable system for performing a laserablation procedure can be found in commonly assigned U.S. Pat. Nos.4,665,913, 4,669,466, 4,732,148, 4,770,172, 4,773,414, 5,207,668,5,108,388, 5,735,843, 5,711,762, 5,219,343, 5,646,791 and 5,163,934, thecomplete disclosures of which are hereby incorporated by reference.

[0053] The computer control system 22 is typically mounted to a baseframe 18 and is preferably coupled to a laser subsystem 13 through alaser alignment system 17. Additionally, the computer control system iscoupled to a patient seat 24 through a patient alignment system 11. Aswill be described more fully below, the patient seat 24, laser deliveryoptics 16, or both, can be moved in response to a control signal toalign the patient's eye E with a laser beam axis 15.

[0054] The operator interface display 23 and the assistant display 34are typically conventional computer monitors. However, the operatordisplay and assistant display can be a touch screen, a computercontrolled timer, an alphanumeric light emitting diode (LED), liquidcrystal display, or the like. The assistant display 34 is used toprovide real-time visual indication to the assistant or observer of theremaining treatment time or other information associated with the lasertreatment. Preferably, the assistant display is a dedicated monitormounted on the arm supporting a laser delivery optics 16 or base frame18 (FIG. 4). However, as shown in FIG. 3, the assistant display can bemounted anywhere that allows the assistant or observer to view theinformation shown on the assistant display while adjacent the patient.

[0055] As illustrated in FIG. 4, the assistant display 34 is typicallymounted on arm 94 and aligned orthogonal to the operator interface 30.Preferably, the assistant display faces toward the patient seat 24,where the assistant station 92 is typically located. The assistantdisplay typically shows the remaining time in characters which areapproximately 20 mm in height. The assistant display preferably has atleast a +/−50° viewing angle 99, but the viewing angle will varydepending on the type of display used and the placement of the assistantdisplay. In some embodiments, the assistant display is rotatable and/ormovable to a different viewing position. A plurality of assistantdisplays can be coupled to the computer to allow multiple observers toview the treatment. For example as illustrated in FIGS. 4A and 4B, afirst assistant display can be programmed to show the time remaininguntil completion of the procedure 95, while a second assistant displaycan be programmed to show a virtual reticle 96, the refractiveinformation 98, or current depth of the ablation (not shown). It shouldbe appreciated that the control system can be configured to display avariety of information on the assistant display 34 and the operatordisplay 23. The displays can display the same information, differentinformation or any combination thereof.

[0056] One embodiment of the assistant display employs a method ofdecoding Binary Code Decimal (BCD) into Seven-Segment Code. The decoderis a combinational circuit that accepts a decimal digit in BCD andgenerates the outputs for selection of segments that display the decimaldigit. Each digit of the display is formed from seven segments (a, b, c,d, e, f, g), each consisting of one light emitting diode (LED) that canbe illuminated by digital signals. The numeric designation chosen torepresent the decimal digits is shown in FIG. 4A. The decoding isperformed inside a programmed logic device (PLD).

[0057] Referring now to FIGS. 5A and 5B, the computer control system 22can be programmed to contain edit fields on the operator interfacedisplay 30 for entering and/or displaying refractive information of thepatient's eye. The control system can be programmed to display the editfields with different colors to provide a display which provides anobvious indication of the refractive information of the eye. The editfields of the system preferably change color to reflect the change insign (negative or positive) of the values that are displayed in the editfield. Edit fields containing myopic refractive values can have a firstcolor 50, while edit fields containing hyperopic refractive informationcan have a second color 52. Because myopic refractive information hastraditionally been associated with the color red, edit fields havingmyopic or negative refractive information preferably have a redbackground. Conversely, edit fields having hyperopic or positiverefractive information preferably have a black background. However, itis contemplated that any combination of background colors can be used todisplay the refractive information. Additionally, instead of having adifferent background colors, the control system can be programmed toprovide different font colors. In most cases, the refractive informationwill still have the preceding “≡” or “−” in addition to the differentcolored backgrounds or fonts.

[0058] The combination of the different colors and leading sign allowsthe operator to easily determine, at a glance, whether the refractiveinformation is myopic or hyperopic, and will allow the operator to alteror stop the treatment if desired. For example, as illustrated in FIG.5A, for an eye having mild myopia with a correction of

[0059] −2.50 diopters the background on an operator display 30 will be afirst color 50. As shown in FIG. 5B, if the refractive property of theeye is corrected to +0.50 diopters, the background will change to asecond color 52.

[0060] Another aspect of the present invention is the addition of anoperator input which provides a pre-determined secondary ablativetreatment of the epithelial layer. The improved operator interfacepreferably supports the “no-touch PRK,” which removes the epitheliallayer with a laser instead of a mechanical scrubber or spatula. In orderto assure uniform removal of the epithelial layer over the entire targetregion, the ablative radiation is typically patterned or adjusted by thecontrol system, as described in U.S. patent application Ser. No.09/022,774, filed Feb. 2, 1998, the full disclosure of which isincorporated herein by reference. However, even with a patterned laser,the first ablative treatment often does not completely remove theepithelial layer from the target region.

[0061] The control system can be programmed to deliver a pre-determinedfirst amount of ablative energy and a pre-determined secondary ablativetreatment. In most embodiments, the secondary ablative treatment is anincremental or smaller dosage of the first ablative treatment.Preferably, the secondary ablative treatment is delivered throughactuation of a “deeper” button at the control station 21. As illustratedin FIGS. 6 and 7, the button can be a physical button 86, an icon 88actuatable by a computer cursor 87, a button 84 on a touch screen, orthe like. As will be described more fully below, actuation of the deeperbutton delivers a secondary ablative treatment without requiring thephysician to reprogram the laser. Once it is determined that theepithelial layer has been completely ablated from the target region, thelaser can proceed to the shaping of the stromal layer.

[0062] Referring again to FIG. 3, the control system 22 is typicallycoupled to the laser subsystem 13 to control the treatment of thecornea. Laser 12 is optically coupled to laser delivery optics 16, whichdirect laser beam 14 along a laser axis 15 to an eye of a patient P.Laser 12 can produce a single beam or multiple scanning beams ofablative radiation. A delivery optics support structure (not shown)extends from a base frame 18 to support the laser. Laser 12 generallycomprises an excimer laser, ideally comprising an argon-fluorine laserproducing pulses of laser light having a wavelength of approximately 193nm. An excimer laser is the illustrative source of an ablating beam,however, other lasers, such as solid state lasers, are equally suitablein the present invention. The laser system may include a variety ofsolid state lasers, including frequency multiplied solid state laserssuch as flash-lamp and diode pumped solid state lasers. Exemplary solidstate lasers include UV solid state lasers (approximately 193-215 nm)such as those disclosed in U.S. Pat. Nos. 5,144,630, 5,742,626,Borsuztky et al., “Tunable UV Radiation at Short Wavelengths (188-240nm) Generated by Sum Frequency Mixing in Lithium Borate”, Appl. Phys.61:529-532 (1995), the full disclosures of which are incorporated hereinby reference. Such lasers include, but are not limited to, alternativelasers providing ultraviolet radiation, for example, solid state lasers,including frequency multiplied solid state lasers such as flash-lamp anddiode pumped solid state lasers, including UV solid state lasers(approximately 193-215 nm) such as those disclosed in U.S. Pat. Nos.5,144,630, 5,742,626, Borsuztky et al., “Tunable UV Radiation at ShortWavelengths (188-240 nm) generated by Sum Frequency Mixing in LithiumBorate,” Appl. Phys. 61:529-532 (1995), the full disclosures of whichare incorporated by reference. Laser 12 will preferably be designed toprovide feedback stabilized fluence of 160 mJoules/cm² at the patient'seye, as delivered via delivery optics. The system may be used withalternative sources of radiation of any wavelength, particularly thoseadapted to controllably photo-decompose the corneal tissue withoutcausing significant damage to adjacent and/or underlying tissues of theeye. Laser 12 and delivery optics 16 will generally direct laser beam 14to the eye of patient P under the direction of a computer 22. Computercontrol system 22 will generally selectively expose portions of thecornea to laser pulses of laser beam 14 to remove the epithelial layerof the target region and to effect re-sculpting of the cornea and laterthe refractive characteristics of the eye. A microscope 20 mounted onthe delivery optic support structure near the control system and abovethe patient's head P, allows the operator to monitor the progress of thetreatment. Other ancillary components of the laser subsystem 13 includea patient eye retention system (not shown), an ablation effluentevacuator/filter 91, as well as the gas delivery system 93.

[0063] Laser beam 14 may be tailored to produce the desired re-sculptingusing one or more variable apertures (such as a variable iris andvariable width slit as described in U.S. Pat. Nos. 5,713,892, 5,711,762and 5,735,843 the full disclosures of which are incorporated herein byreference), by varying the size and offset of the laser spot from theaxis of the eye (as described in U.S. Pat. No. 5,683,379, and alsodescribed in co-pending U.S. patent application Ser. No. 08/968,380,filed Nov. 12, 1997, the full disclosures of which are incorporatedherein by reference), by scanning the laser beam over the surface of theeye and controlling the number pulses and/or dwell time (as described byU.S. Pat. No. 4,665,913, the full disclosure of which is incorporatedherein by reference), using masks in the optical path of laser beam 14which ablate to varying the profile of the beam incident on the cornea(as described by U.S. patent application Ser. No. 08/468,895, filed Jun.6, 1995, the full disclosure of which is incorporated herein byreference), or the like. The computer programs and control methodologyfor each of these re-sculpting techniques is well described in thepatent literature. Additional optical components may also be included inthe optical path of laser beam 14, such as integrators to spatiallyand/or temporally control the distribution of energy within the laserbeam (as described in U.S. Pat. No. 5,646,791, the disclosure of whichis incorporated herein by reference), and the like.

[0064] Referring again to FIG. 3, computer control system 22 ispreferably coupled to both a patient alignment system 11 and a laseralignment system 17 to align the laser beam axis with a first opticalaxis of a first eye. The head of patient P can be firmly supported onand preferably restrained by a contoured patient seat 24 to support apatient in position so that first and second eyes of the patient arenear first and second nominal optical axes.

[0065] Positioning of the eye E relative to the laser delivery optics isgenerally effected by movement of the patient seat 24 into substantialalignment with the laser beam axis 15. The patient is generally layingdown or reclined in a supine position. However, in alternativeembodiments the patient is oriented in an upright seated position (asdescribed in U.S. Pat. No. 5,795,351, the full disclosure of which isincorporated herein by reference).

[0066] Patient alignment system 11 preferably comprises a grossadjustment mechanism 26 having an activating motors to move the seat orbed in the X, Y and Z direction. The gross adjustment mechanismstructurally couples the seat to the laser and can be actuated by asignal from the control system or manually actuated by a joystick 25 tomove the patient seat along at least the X and Y horizontal directionsto align the patient's eye with the laser beam axis (FIG. 7A).

[0067] The optical system and/or the laser delivery optics 16 can bemoved with a fine adjustment mechanism 28 of the laser alignment system17 to align the laser beam axis 15 with the first optical axis 80 whilethe patient is supported on the patient seat. If the laser deliveryoptics are to be moved, the objective lens of the microscope willpreferably remain affixed relative to at least a portion of the laseroptical train adjacent the eye so as to maintain alignment between themicroscope field of view and the laser treatment site, as described inco-pending U.S. patent application Ser. No. 09/105,073, filed Jun. 26,1998, the full disclosure of which is incorporated herein by reference.The fine adjustment mechanism 28 can be manually actuated or computeractuated to finely move the laser delivery system to fully align the eyewith the laser beam (FIG. 3). Typically, the fine adjustment mechanismis comprised of an activating motor which can move the laser deliveryoptics in the X, Y, and Z direction. Typically, the fine adjustmentmechanism uses the same joystick and moves the laser optics at a slowerspeed. In alternative embodiments, the fine adjustment mechanism can becoupled to the patient seat to finely align the patient's eye with thelaser by making minute adjustments to the seat. Preferably, when thefine adjustment is coupled to the seat, the same joystick and activatingmotor are used, but the motor is adapted to move at a lower speed.

[0068]FIG. 7A illustrates a typical joystick setup. Preferably, thejoystick 25 is located at the operator's station 21 and adjacent themicroscope 20. The joystick adjusts the position and orientation of thepatient chair and/or the laser optics. Typically, movement of thejoystick is progressive, i.e., the farther the joystick is moved fromthe rest position, the faster the chair moves. In a preferred setup,movement of the joystick to the left causes the patient chair to move tothe right, and vice versa. Movement of the joystick forward moves thepatient toward the operator, and vice versa. Turning of the joystickhandle clockwise can move the patient chair upward and vice versa.However, alternative setups are equally suitable in the presentinvention. For example, an alternative setup can include moving thejoystick to the left to move the patient to the left and moving thejoystick forward to move the patient away from the operator.

[0069] FIGS. 8A-8G illustrate a preferred embodiment of the movablepatient seat. As shown in FIG. 8A, the patient seat 24 is mounted tobase 40 through a gross adjustment mechanism 26. A chair release pedal53 is typically located at the base. To lock the chair, the operator canpress the right side of the pedal. This can prevent the chair frompivoting outward and can prevent the chair main body from being raised.To unlock the chair, the operator can press the left side of the pedal.

[0070] The patient seat or bed typically comprises a head rest 42, amain body 44, and a lower support 46. The head of patient P will befirmly supported by, and preferably restrained by a contoured head rest97. Preferably, the contoured head rest comprises an adjustable vacuumpillow or cushion which conforms to the patient's head to stabilize thepatient's head in position. The pillow can be adjusted for comfort,angle, support and stability. As shown in FIG. 8B, the vacuum pillow 97is positioned around and under the patient's head P to support thepatient. After the patient is placed on the pillow, the operatorconnects a vacuum pillow suction tubing to the pillow and a suctionport. The operator turns on a suction pump with a pillow suction button(not shown), and after about five seconds, the pillow hardens andconforms to the patient's head.

[0071] As shown in FIG. 8C, chair headrest controls 55 are preferablylocated underneath the chair headrest to further align the patient'shead. Chair headrest controls typically comprise at least two knobs foradjusting the headrest. The head-tilt knob 57, controls the angle of thepatient's head. Typically, an operator can turn the knob clockwise toangle the top of the patient's head upward. The neck-tilt knob 59controls the angle of the patient's neck. Turning of the knob clockwiseangles the patient's neck upward.

[0072] As shown in FIG. 8A, gross adjustment mechanism 26 is coupled tothe control system and is adapted to move the patient seat in at leastthe X and Y horizontal directions and rotate the seat about at least oneof the X, Y, and Z axes. In alternative embodiments, the patient seat ismovable in both the horizontal and vertical directions 79 (X, Y, and Z)to axially and laterally align the first optical axis with the laserbeam axis (FIG. 8A).

[0073] The control system will typically be programmed to automaticallymove patient seat 24 from a loading position (FIG. 8D) to a firstnominal position (FIG. 8E). Preferably, the first nominal positionplaces the seat in a nominal “X”, nominal “Y”, and a nominal “Z”position such that the seat is generally near the center of the X, Y,and Z directions and the patient's first optical axis 80 issubstantially aligned with the laser beam axis 15. However, the firstoptical axis will not be always be completely aligned with the laserbeam axis 15. As long as the nominal position is within the range ofmotion 65 of the laser alignment system, the first optical axis 80 canbe properly aligned with the laser axis by making adjustments to thefine adjustment mechanism. If fine adjustments are required, theoperator can manually adjust the fine adjustment mechanism by actuatingthe joystick to align the patient's eye with the laser. The operator canmanually view the alignment of the laser through the operator interfacedisplay 30 or the microscope before the patient is on the seat or bed.Alternatively, the computer control system can be programmed toautomatically actuate the fine adjustment mechanism to align the laserbeam axis with the first optical axis of the patient's eye. FIG. 8Fillustrates the laser axis completely aligned with a patient's firsteye.

[0074] As shown in FIG. 8G, the control system can also be programmed toautomatically move to a second nominal position to align a secondoptical axis 82 (i.e. patient's second eye) with the laser beam axis 15.The control system can be programmed to automatically align the secondoptical axis with the laser beam axis immediately after treatment of thefirst eye or to directly align the second optical axis with the laserbeam axis. For example, the control system will often be programmed tohave the first nominal position align over the patient's right eye.However, in situations where only the left eye is treated, the controlsystem can be programmed in various ways. Alignment can be accomplishedby initially moving to the first nominal position (alignment with righteye) and then immediately moving to the second nominal position(alignment with the left eye). Alternatively, the system can beprogrammed to move directly to the second nominal position. Preferably,the control system can move the patient seat or laser optics to a secondnominal position so that the patient's second eye is completely alignedwith the laser beam axis. If the eye is not completely aligned with thelaser, the operator should not be required to manually realign thepatient seat with the gross adjustment mechanism, as the second positionwill typically be in the range of motion of the fine adjustmentmechanism. If adjustments are required, the operator can manually adjustthe laser optics, manipulate a computer input device (i.e. joystick) toalign the laser axis with the patient's second eye, or allow the controlsystem to automatically align the laser axis with the second opticalaxis.

[0075] Referring now to FIG. 9, the computer 22 is coupled to the lasereye system 100 to control the laser eye treatment. Using input devices33, the operator can manually input the number of laser pulses, thedesired patterning of the laser, and the like. The information willgenerally be shown on the operator interface display 30 and/or theassistant display 34. Typically, a laser monitoring system 21 monitorsthe eye during the treatment and sends the information to the computerfor display on the operator display and/or the assistant display. Thelaser monitoring system 21 can include of a video camera, sensors, seatposition sensors, beam position sensors, or the like. The computercontrol system will preferably be programmed to display the refractiveinformation, the remaining time, a virtual reticle, and the like.

[0076] The operation of a typical procedure will now be described indetail. As illustrated in FIGS. 9 and 10, the patient is initiallyseated in the patient seat 24 (Step 101). Preferably, the chair isunlocked using the chair release pedal, and the chair can be allowed torotate outward, upward, or away from the laser. Typically, the chair ismoved to a sitting position by pressing a switch on the chair headrest.The chair can then be moved to a reclining position by pressing a switchon the headrest. Using a joystick, the chair can be lowered to itslowest position to allow the patient to be moved beneath the laser. Atsome point prior to aligning the patient's eye with the laser, thepatient's head can be stabilized using a vacuum pillow, as describedabove.

[0077] Next, the operator can actuate the computer control system (Step102) to send a nominal position control signal to the laser alignmentsystem 17, the patient alignment system 11, or both, to align thepatient in a first nominal position (Step 104). Preferably, the operatorsimply actuates input devices such as a fixed button, a touch screen, ormenu selection on the operator display, to move the patient to the firstnominal position and align the laser axis with the first optical axis.If the patient's eye is aligned with the laser axis, the operator willproceed to epithelial treatment (Step 108). However, in some situations,the patient will not be completely aligned with the laser axis. Sincethe patient is within the range of motion of the fine adjustmentmechanism, the operator can actuate the control system to send a signalto the fine adjustment mechanism to completely align the laser with thefirst optical axis (Step 114). Alternatively, the operator can manuallyalign the laser axis with the eye by actuating a joystick. After properalignment is achieved, the laser can be activated through the laseroperation controls 23 to perform the epithelial treatment (Step 116).

[0078] If a photorefractive keratectomy(PRK) is performed, the operatorcan use the laser operation controls to remove the epithelial layer fromthe target region prior to shaping the stromal layer. As illustrated inFIGS. 11 and 11A, a pre-programmed first tissue ablative beam 75,typically a uniform beam, can be delivered over the target region of theepithelial layer 70 (Step 119). If the epithelial layer is completelyremoved, the operator can proceed to stromal re-sculpting (Step 130).However, as illustrated in FIG. 11B, the first ablative treatment 75often leaves a portion of the epithelial layer 73 in the target region71. If it is determined that that the first ablative treatment wasinadequate (Step 120), the operator can actuate the deeper button (Step122). Actuation of the deeper button delivers a predetermined secondaryablative treatment 77 to remove the remaining epithelial layer 73 fromthe target region 71 (Step 124). Typically, each secondary-ablativetreatment is an incremental or shorter dosage of the first ablativetreatment and is typically programmed to remove between 1 μm to 15 μm,and preferably between 5 μm to 10 μm of the epithelial layer. Theoperator simply presses the deeper button to deliver the secondaryablative treatment. After the delivery of the secondary ablativetreatment, the operator can monitor the epithelial layer to determine ifthe secondary-treatment was adequate (Step 126). If the treatment wasadequate, the operator can proceed to the stromal re-sculpting, tocorrect the vision errors (Steps 128). However, if the secondarytreatment was inadequate, the operator can actuate the deeper button todeliver the pre-programmed secondary ablative energy (Step 122). In apreferred embodiment, the control system can be programmed to limit theamount of secondary-ablative treatment to that of approximately 25 μm.Preferably, this is achieved by limiting the amount of times the deeperbutton can be actuated. For example, the computer can be programmed toallow the operator to press the deeper button a 3 times (Step 132)before having to manually re-program the laser to remove the remainingepithelial tissue (Step 134). This safety feature can help avoid theinadvertent ablation of the underlying stromal layer.

[0079] Some embodiments of the system allow the operator to program thepower, patterning of the laser, time of ablation, depth of epithelialtissue to be removed, and the like. For example, if the first ablativetreatment removes 35 μm of the epithelial layer, and the operatorpresses the deeper button and removes 10 μm of the epithelial layer, theoperator can program the next ablative energy to ablate between 1-5 μm.Alternatively, the operator can pre-program the deeper button to deliveronly 5 μm for every secondary ablative treatment. Moreover, the controlsystem can be programmed to reduce each subsequent secondary ablativetreatments. For example, the initial secondary ablative treatment can beprogrammed to ablate 10 μm of the epithelial layer, the subsequenttreatments can be programmed to ablate 5 μm of the epithelial layer, andso forth. Preferably, the control system can monitor the ablation of theepithelial layer and display on the operator display the progress of theablation.

[0080] Once the epithelial layer has been completely removed theoperator can proceed to the stromal re-sculpting. Typically, the controlsystem will display a treatment screen having refractive information,treatment time, or the like. A sample treatment screen is shown in FIG.12.

[0081] While the above is a complete description of the preferredembodiments of the invention, various alternatives, modifications, andequivalents may be used. Therefore, the above description should not betaken as limiting the scope of the invention which is defined by theappended claims.

What is claimed is:
 1. A method of positioning a patient for refractiveeye surgery, the patient having first and second eyes, the methodcomprising: automatically positioning the patient in a first nominalposition, in the first nominal position the patient's first eye issubstantially aligned with a laser beam axis; and moving the patient ina second nominal position, in the second nominal position, the patient'ssecond eye is substantially aligned with the laser.
 2. The method asrecited in claim 1, wherein the moving is carried out after the firsteye has been treated.
 3. The method as recited in claim 1 whereinpositioning is carried out by moving a patient seat.
 4. The method asrecited in claim 3, wherein the nominal positions are near a center ofthe seat's X and Y horizontal directions of movement.
 5. A method ofaligning a patient for laser surgery, the method comprising: placing aseat in a patient loading position; and activating a control system tomove the seat to a first nominal position, wherein the seat in the firstnominal position substantially aligns a patient's eye with a laser beamaxis.
 6. The method of claim 5 wherein placing comprises rotating theseat to an upright position.
 7. The method of claim 5 further comprisingmaking fine adjustments to at least one of a laser optics and thepatient seat to align the patient's eye with the laser beam axis.
 8. Themethod of claim 7 further comprising activating the control system tomove the seat to align the patient's other eye with the laser beam axis.